November 2024

October 2024

September 2024

August 2024

July 2024

June 2024

May 2024

April 2024

March 2024

February 2024

January 2024

Science: Climate Change, Primates, Tardigrades

By Bob Snodgrass
Posted: 08/10/2021

Present: Barbara M, Sharon J, Sally A, Howard R, Bruce G, Lucinda H, Bob S

We had a pleasant meeting prolonged by my difficulty showing my ‘squirrel movies’ on Zoom. Sharon began by returning to the subject of cells which are half human and half monkey, created in China this year. In the lab, chimeric animals are created by injecting cells from one species into the embryo or fetus of another. The first chimeric mice were created in the 1960s. Nicole Le Douarin, a well-known French developmental researcher, used quail-chick chimeras for more than 40 years to produce significant information about the origin and development of neural crest, immune and hematopoietic cells.

 

Workers tried to produce human-rodent chimeras more than 20 years ago but couldn’t get survival of human cells in rodent, chick or pig embryos. Now, Chinese researchers with help from a US Salk Institute researcher, have produced human-monkey chimeras which survived up to 20 days, using techniques they had first published in 2017 when they tried human-mouse chimeras, but obtained no more than 1% surviving human cells. Now they used cynomolgus monkeys.

 

The researchers injected each of 132 six-day-old monkey embryos with 25 human EPS cells, a special kind of stem cell, The next day, they found human cells in all of the embryos. Where those cells were found within the embryos shifted over time. At 20 days old, the three surviving chimeras had up to 7% of cells that were human derived- not many and notice how few chimeras survived.

 

Various organizations produce standards for animal research. They have only persuasive powers. A Chinese scientist used Crispr techniques to edit the germ line of twin girls in attempt to protect them from HIV by recreating a mutation in the CCR5 gene which makes humans resistant to HIV infection. That scientist, He Jiankui, is now in jail along with one of his collaborators. It appears he fabricated informed consent papers and probably created a different mutation in the CCR5 gene, potentially harming immune function without achieving immunity to HIV. Scientists all around the world quickly turned against Jiankui claiming that his approach had never been tested and that he took advantage of the twin’s mother.

 

Human-monkey chimeras are a different situation. The primary motivation was to ultimately create organs for transplantation into humans. The source can’t be other primates. The approach used here, only partially successful, would have to be modified for pigs. Success is many years away but there has been no question of fabricating data. Researchers will not be able to obtain government funds for this work. However, there was no uproar among the scientific community when the recent paper was published in Cell, a widely read journal. I would be surprised if the scientists responsible for this work were reprimanded or punished. Several religious groups have spoken out against it, but fewer religious organizations than spoke out against Jiankui’s work. Fewer people place a high priority on this.

 

Barbara reported next on a related topic: most Western countries now restrict primate research severely and these restrictions will probably increase. China and Japan do not. This seems most relevant to brain research because pig hearts and livers are similar to ours; there are major differences in brains. Hence, some organizations are upset out about our losing our lead in brain research (the US & Europe.). Prominent organizations to which I belong (American Academy of Neurology, the American College of Neuropsychopharmacology, the American Physiological Society, the American Society for Microbiology, the American Transplant Foundation, the Endocrine Society, the Federation of American Societies for Experimental Biology, and the Society for Neuroscience*) have lobbied Congress extensively and written things aimed at patients. They are behind some of this talk. I expect further restrictions in primate use, but not its elimination. Organizations such as PETA may grow in influence. I don’t see disastrous problems in the next 20 years. It is still the case that much research, including primate-based research, looks pedestrian a few years late. Until we see Americans going to China and Japan for postdoctoral training, I won’t worry.

 

Howard spoke next about the widespread consequences of climate change: more and more extreme prematurity in humans (this is heavily influenced by environment and SES) There are reliable reports of aberrant bird migration and increasing death rate in sea animals from whales/dolphins to shrimp and krill. Information on the survival of deep sea animals isn’t available. Some of these effects are likely due to toxic chemicals, whose use has increased along with climate change. Toxic chemicals are much better regulated in the EU than the US.

 

We no longer hear sensible Republicans claiming that climate change is a hoax or will benefit crops. However almost all strongly defend the extraction and use of fossil fuels. This is a problem with our closely divided government and the possibility of Republican gains in the 2022 midterm elections.

 

Bruce wanted to know how a man with a reportedly small prostate could have a normal sized prostate in later life. First, urologists are the only physicians trained to estimate prostate size and secondly, the prostate grows with age. This is an effect of androgenic hormones.

 

Lucinda followed up Howard’s point with comments about Monarch butterflies. The numbers of these beautiful creatures have decreased at least 80% since 1980. New overwintering sites in Mexico have been discovered. This may not reflect aberrant migration; climate change and pesticide use have made some sites less appealing. The Xerxes society is making an effort to save the monarchs, who are in trouble.

 

I tried to show an image of tardigrades which several people didn’t see. I tried unsuccessfully to recover it, failing because I had misspelled tardigrade. Tardigrades are probably the toughest creatures on Earth, and now we know how they can survive years of complete dehydration. Water bears, or tardigrades, have been recorded surviving the vacuum of space, high doses of radiation and pressure. Several papers have reported that they survive dehydration by turning into glass, which is a misunderstanding of the word vitrification. Their tardigrade-specific intrinsically disordered proteins (TDPs) are essential for desiccation tolerance. These genes are turned on with dehydration, forming non-crystalline amorphous solids leaving no free water in the cytoplasm. Here’s the picture. The uniquely high content of these disordered proteins and their ability to turn on quickly  must be an evolutionary adaptation.

 

Fortunately I eventually figured out how to show my movies of jumping squirrels on the Berkeley campus, who utilized the Parkour maneuver which they had never seen, when the distance between the jumping place and the landing place became more than about .8 meters. This was described in a paper in Science. I’ll send the two movies and the paper to anyone who wants it. I enjoy watching the movies again and again.